The study of individual cells and mixed populations of cells provides a powerful approach to unraveling the simultaneous effects of paracrine, juxtacrine, and matrix-associated factors in the poorly understood cellular processes that underlie normal and pathophysiological processes such as osteoblast differentiation and age related bone loss. In many cases, progress in the purification of progenitor cells and rare stem cells has outpaced development of technologies for gathering and interpreting information at the individual cell level. This proposal focuses on the development of tools for real time study of individual cells and mixed populations of cells in automated combinatorial cell culture systems. Goals include: 1) Development of software for real time analysis and dynamic manipulation of osteoblast progenitor/precursor cells; 2) Development of devices and procedures for coherent real time detection of phenotypic changes in rare human cells and the progeny of such cells deposited, tracked, imaged, and analyzed individually through time; 3) Innovation of technologies for real time quantitation of cellular protein production through miniaturized assay methods and off-line analytical systems; and 4) Application of these technologies to determine effects of aging on osteoblast differentiation potential of human bone marrow stromal cells, utilizing the subset, STRO-1+, in an in vitro model system. The tools developed in this project will provide valuable resources for a wide range of disciplines involving the study of cellular interactions and behaviors within various tissues.